A switching device, in particular a protective switching device, having a latching mechanism is used, for example, as a circuit breaker. Circuit breakers—also referred to as automatic circuit breakers—are predominantly used today in place of fuses.
Circuit breakers are overcurrent circuit breakers having a first and a second tripping device which act on a latching mechanism. An electromagnetic tripping device effects instantaneous tripping in the event of a short circuit. A thermal bimetallic tripping device switches off in the event of permanent overloads when the affected line is excessively heated. The latching mechanism can also be actuated by a manually operable switching toggle, by which the respective circuit breaker can also interrupt a circuit.
A circuit breaker having a latching mechanism, which has a moveable contact arm, a tripping lever, a latch and two or more frame parts, is disclosed in U.S. Pat. No. 4,968,863. Forces occurring between the parts of the unit in this case run largely in one plane. The moveable contact arm and a torsion spring of the latching mechanism are in this case mounted on a pin such that they can pivot.
A mass-produced product such as a circuit breaker is subject to market-related and cost-restrictive factors which have a considerable effect on the number of components used in the device. The circuit breaker of the previously cited prior art does have, however, a number of device components which is unfavorable in respect of these factors.
Furthermore, a circuit breaker latching mechanism with a reduced number of parts is disclosed in DE 1 904 731. This latching mechanism has a unit which essentially includes a moveable contact arm, a tripping lever and a latch. In this case, the moveable contact arm is mounted on a pin.
An important criterion for the operational reliability of a circuit breaker is a so-called back-latching between the tripping lever and the latch. However, an element for assisting with this operation is not provided.
DE 33 39 398 A1 likewise discloses a circuit breaker having a latching mechanism. The latching mechanism has, at least in one section, a plastic part. The plastic part, however, owing to its proximity to the point of contact, must be made of a particularly durable and therefore expensive material.